JPH11314960A - Ceramic sintered body and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ceramic sintered body contg. corrosive NaCl and KCl separately allowed to enter into solid solns. in a glass phase at a low cost by pulverizing ash generated by the incineration of municipal garbage, adding specified amts. of an SiO2 -contg. material and a dry powder to the pulverized ash and collected flying ash and carrying out kneading, molding and firing. SOLUTION: Ash generated by the incineration of municipal garbage is screened into parts of <1 mm, 1-5 mm and >5 mm and the parts are separately pulverized to <=60 mesh and the resultant fine powders are blended in a ratio according to the desired compsn. The blend is further mixed with flying ash if necessary and 1 pt.wt. of the prepd. powdery material is mixed with 0.5-1 pt.wt. water to prepare a slurry. This slurry is mixed with 3-8 pts.wt. material contg. >=60% amorphous SiO2 , e.g. zeolite based on 1 pt.wt. NaCl and KCl, the slurry is then cured for 1-24 hr and the resultant body is kneaded with a dry powder such as slag, dried and fired to obtain the objective ceramic sintered body contg. NaCl and KCl separated allowed to enter into solid solns. in an SiO2 -Al2 O3 -Na2 O glass phase. The glass phase is contained by 5-80 wt.% of the total amt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the utilization of garbage incineration ash, which is discharged every year from cities and all over Japan in an amount of 5,000 tons or more. In other words, wastes are disposed of at high cost under strict control such as elution of heavy metals, and the reuse of resources is an important national theme. The present invention relates to a ceramic sintered body suitable for remanufacture as a construction material such as a plate, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Municipal refuse incineration ash is produced by mixing various substances at an unstable ratio. When metals are removed, the remainder is debris, glass waste, ceramic waste and paper, wood, plastics and households. The garbage discharged from the garbage is incinerated into ash. In particular, ash (bottom ash) of 1 mm or less and fly ash (EP ash) scattered and collected during incineration are obtained by adding lime to neutralize hydrogen chloride and the like. Contains salt (NaCl), potassium chloride (KCl) and chlorides of heavy metals. for that reason,
When a ceramic product is manufactured using these materials as raw materials, in particular, the firing furnace and the furnace material are significantly damaged by the evaporation of the salt, and the salt remains in the sintered product to lose its commercial value.
However, the prior art has not sufficiently solved the drawbacks and problems in this kind of industrial production.

[0003] As an example of a relatively high level of the prior art for solving the above-mentioned problem, Ceramic Society of Japan 86 [6] 197
8 is described. This is an announcement of a prototype technology for producing artificial lightweight materials and tiles using a raw material mainly composed of debris, glass chips, etc., excluding ash of 1 [mm] or less. In this study, a small amount of ash of 1 [mm] or less was used as a carbon component for weight reduction.
aCl almost remains in the product with its chemical composition.
When the product absorbs water, NaCl elutes, causing a problem that salt is deposited on the surface. Another example of the prior art is as follows. Because of the low bulk specific gravity of municipal garbage incineration ash and the restriction of elution of heavy metals, this conventional technique merely implements a method of melting these to try to reduce the volume. This technique requires a large amount of cost for the melting operation, and the molten slag that is melted is used only for low value-added applications such as roadbed materials for construction. Yet another prior art is a salt glaze product. In this method, NaCl is injected into the grate and salt vapor is sent into the furnace. Furnace material is remarkably depleted, and in recent years, the production of this type of salt glaze products has been difficult due to the harmfulness of chlorine in the exhaust gas. Has declined greatly and is only used in some pottery production.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to the treatment of the residue of salt as it is in the prior art treated material, which is the secondary pollution of the refuse incineration ash, or the treatment of an incinerator with unresolved salt. In addition to solving the problem of erosion, ceramics that produce high-value-added construction ceramic products directly from incinerated ash that is not available in the prior art, perform permanent recycling, and dramatically reduce waste disposal costs It is an object of the present invention to provide a sintered compact and a method of manufacturing the same.

[0005] This will be described more specifically. Municipal garbage incineration ash has considerable component differences depending on the region or the incinerator incineration method. In the present invention, the incineration ash generated in a large city is reduced to 0.5 [mm] or less, 0.5 [mm] to 1.0 [m].
m], 1.0 [mm] to 2.0 [mm], 2.0 [m
m] to 5.0 [mm], 5.0 [mm] to 10 [m
m] and 10 [mm] or more, and then sieved to 60 [mesh] or less and subjected to chemical analysis, X-ray diffraction and thermal analysis of each particle size category. mm]
In the following, it was found that when stratified into three sections of 1 [mm] to 5 [mm] and 5 [mm] or more, the fluctuation range of the chemical component was small, and it could be used as a raw material for a sintered body. Further, the presence of NaCl and KCl was pursued by X-ray diffraction, but almost all of them were present in ash and fly ash of 1 mm or less, as shown in Table 1.

[0006]

[Table 1]

[0007] From these results, the incinerated ash produced with a particle size of 1 [mm] or more contains very little NaCl or other salts and has a chemical composition of 1 [mm] to 5 [mm].
[Mm], layered pulverized material of 5 [mm] or more are used at respective mixing ratios. However, the main object of the present invention is to provide a physical and chemical measure against ash and fly ash of 1 [mm] or less containing NaCl and other salts.

[0008]

Structure of ceramic sintered body of the present invention According to an aspect of the first NaCl and KCl from municipal refuse incineration ash in the glass phase of _{SiO 2 -Al 2 O 3 -Na 2} O -based The glass phase is decomposed to form a solid solution, and the glass phase is contained in an amount of 5% by weight or more and 80% by weight or less of the whole.

Next, in the method for producing a ceramic sinter according to the present invention, waste incineration ash is sieved with a sieve of less than 1 mm and 1 to 5 m.
m] and particles exceeding 5 [mm], and then each of the sieved materials was separately collected by a finely pulverized powder of 60 [mesh] or less and / or a dust collector of a garbage incinerator. If necessary, the fly ash is mixed, and then 0.5 to 1 part by weight of water is added to 1 part by weight of the adjusted powder material, and further mixed to form a mud. The anhydrous NaCl in the mud is added. And 1 part by weight of KCl component and 60 parts by weight of amorphous SiO ₂
[%] 3 to 8 parts by weight of a material containing at least
After curing for more than 24 hours to form a primary raw material base, 3 parts by weight of the primary raw material base is mixed with one or more dry powders selected from slag, selven, glass cullet, and clay. Is added and kneaded as a secondary raw material in an amount of 0.5 to 1 part by weight.
After drying at a temperature of 200 ° C. or lower for 1 hour to 24 hours, baking is performed at a temperature of 900 ° C. to 1200 ° C. Further, as the details of the method for manufacturing a ceramic sintered body of the present invention,
The material containing at least 60% by weight of amorphous SiO ₂ is at least one selected from zeolite minerals such as high silica type clinoptilolite, diatomaceous earth, acid clay, fly ash and volcanic ash. It is characterized by being a material.

The above configuration will be described in more detail. N
The reason that the range in which the glass phase in which aCl and KCl are decomposed and solid-solved are contained in the sintered body is wide is that the component range of the dust itself is very wide. Range. Further, in the production method of the present invention, the sieving treatment of the refuse incineration ash into 1 to 5 [mm], less than and more than 1 [mm] is performed when NaCl confirmed by X-ray diffraction is 1 [mm] or less. This is due to the large number of particles. The reason that the amount of the amorphous SiO ₂ material added to the incinerated ash mud is 3 parts by weight or more with respect to NaCl and KCl in the anhydride in the mud is not more than 3 parts by weight in order to dissolve and stabilize Na ions. This is because the generation of the SiO ₂ —Al ₂ O ₃ —Na ₂ O-based glass phase becomes insufficient. The reason why the content is set to 8 parts by weight or less is that NaCl and KCl in the incineration ash are about 20 [%] in the maximum case, and even if added in excess, the glass phase is generated and becomes extra. is there. The reason why the firing temperature after drying is set to 900 [° C.] or higher is that, in many cases, the glass phase is not sufficiently formed even with a low melting point. This is because, if the temperature exceeds the limit, Na evaporates and damages the equipment.

Next, claim 1 will be specifically described. The necessity to include high silica type clinoptilolite, which is at least four times the soluble salts content in the incineration ash component, is due to SiO ₂
The ratio of SiO ₂ to Na ₂ O in the —Al ₂ O ₃ —Na ₂ O-based glass composition is suitably in the range of 4: 1, and zeolite minerals, diatomaceous earth, acidic clay, etc. have SiO ₂ of 65% or more. The maximum salt content in incinerated ash of 1 [mm] or less is 20 [%]. In addition, the composition of a ceramic sintered body as an industrial product is limited to a maximum of 30% of incineration ash of fine powder due to economical firing temperature conditions and working conditions of powder pressure molding. The content is about 6 [%] at the maximum. On the other hand, zeolite minerals
O ₂ containing 65% or more, and about 4 times as much Si as a composition
It is based on the calculation that 30 to 40% of O ₂ should be incorporated to introduce O ₂ .

Next, claims 2 and 3 will be described more specifically. First, the soluble salts are eluted with water to dissociate and adsorb to particles such as zeolite minerals. Water having a weight ratio of 50% or more is added to form a mud-like form and sufficiently dissociated. Next, when a dry powder such as a zeolite mineral is added and mixed and kneaded, a kneaded clay in a wet state is obtained. Curing time of at least one hour is required for particles such as zeolite mineral, diatomaceous earth, and acid clay to sufficiently adsorb soluble salts into pores. When the adsorption of these clays is completed, the clay, the sintering modifier, and the raw material of the coarse particle portion in the incinerated ash are mixed together with the clay, and the forming moisture is corrected as necessary. Then, a compact is formed. The firing is performed using a roller hearth kiln or a tunnel kiln in the same manner as general ceramics, at 900 ° C. or more and 120 ° C.
The sintering is performed at 0 [° C.] or less without evaporating and scattering NaCl and KCl.

Further, the constitutive theory of the present invention is supplemented. Among the soluble salts concentrated in the incinerated ash fine powder, salt (NaCl), in particular, is a strong ionic complex but has the property of easily dissociating in the presence of moisture. In addition, zeolite minerals such as high silica type clinoptilolite, characteristic pore and lattice structures such as diatomaceous earth, adsorption characteristics to salts and gases, continuous release of water of crystallization during the heating process and non- It is configured to stabilize sodium chloride (NaCl) and other salts in the structure of the sintered body in combination with the change characteristic of forming a solid phase gel having a high content of SiO ₂ by crystallization.

As described above, acidic clay has poor adsorption performance, but has a high content of soluble SiO ₂ and is excellent in the action of producing a glass phase by reacting with NaCl. NaCl
Melts at a melting point of 801 [° C.], but gradually evaporates as salt vapor as the temperature rises, and continues up to about 1400 [° C.]. NaCl has long been used as salt glaze as a solubilized coating for ceramic tubes and tiles. This theory states that A
When salt vapor is brought into contact with a high silica composition having a ratio of l ₂ O ₃ to SiO ₂ of 1: 4 to 12 at a high temperature of 1100 [° C.] or more, chlorine is decomposed and Na ions are converted to SiO ₂ and Al. ₂ O
₃ reacts with Na ₂ O to be fused and coated on the surface as a glassy glaze [Metal Industry Handbook P1
218].

The operation of the present invention is completely different from the operation of a conventional product or a conventional production method, and the salt present in the composition is reacted and decomposed in the composition without evaporating as much as possible in the furnace, and the glass phase is produced. And the effect of minimizing the release of dissociated chlorine from the furnace.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the premise of an embodiment of the present invention will be described. In order to confirm the reaction between salt and these minerals, three types of high silica type clinoptilolite, Otani stone, diatomaceous earth and acid clay from Tochigi prefecture, were converted into dry powder of 0.5 [mm] or less and 20 [%]. After being adsorbed in a saline solution, a dry-pressed test specimen as a dry powder was 700
It was calcined at each of [° C.], 900 [° C.], and 1000 [° C.], and the presence of NaCl was confirmed by X-ray diffraction. The results are shown in Table 2. Note that the N
The content of aCl is 6 [%].

[0017]

[Table 2]

As shown in Table 2, 9
At 00 [° C.], Oya stone loses NaCl, but diatomaceous earth partially remains, and acid clay remains unreacted and almost remains. When the temperature reaches 1000 ° C., the reaction is completed and NaCl
Disappears completely. For this reason, Otani stone, a zeolite mineral, has the highest reactivity. Further, these samples were transferred to PH6
・ After immersing in clear water of 7 for about 24 hours to absorb water sufficiently,
When heated and boiled in hot water, bubbles were observed for a long period of time from the Otani stone sintered body, and the pH of the water after cooling changed to 5.9 to 6.2, which was acidic. However, these phenomena were not observed in diatomaceous earth and acid clay. Considering these reaction mechanisms, in the case of Otani stone, which is a zeolite mineral, NaCl adsorbed on particles was dissociated into Na ions and Cl ions by water vapor continuously released to about 700 ° C in the heating process. In state. On the other hand, the pores of the Otani stone particles are expanded by thermal expansion. In particular, the presence of water at a high temperature promotes the ion exchange reaction and causes Na ion, Cl
The ions are taken into the pore lattice, and when the temperature rises and exceeds 700 ° C., an amorphous solid gel is formed, and SiO ₂ and Na ions having high reaction activity react to form SiO ₂ −.
Generating a Al ₂ O ₃ -Na ₂ O based glass phase. On the other hand, some of the adsorbed Cl ions are volatilized and released, but it is presumed that most of the adsorbed Cl ions remain enclosed in the glass phase as independent bubbles, and Cl ions are gradually released by boiling with boiling water as described above. It appears as a phenomenon. In the case of diatomaceous earth and acid clay, the reaction due to the formation of a glass phase at 900 ° C. or higher is observed in the same manner as in Oyaishi, but the phenomenon of enclosing Cl ions is not observed.

[0019] In the incineration ash of municipal waste, which is the main object of the present invention, 1
The fine powder portion and fly ash below [mm] vary depending on the region and the conditions of the firing furnace.
5%, ZnCl ₂ , Cd as heavy metal chlorides
It is contained as soluble salts such as Cl ₂ and PbCl ₂ , all of which are easily adsorbed on particles such as zeolite minerals like NaCl. Further, the generated SiO ₂ -Al ₂
It is a component that easily reacts with an O ₃ —Na ₂ O-based glass phase. Further, since lime is used for neutralization of fly ash, a large amount of CdCl ₂ is contained in the CaO component, and the generated glass phase is SiO ₂ —Al ₂ O ₃ —CdO—Na ₂ O.
System.

Example 1 Fly ash (EP ash) collected from an urban refuse incinerator was used by removing the mixture with a 100-mesh sieve. The NaCl + KCl in these ashes is about 1
2 [%] and other salts contain 6 [%].
As the zeolite mineral, amorphous SiO ₂ is mainly 70
Oya stone from Tochigi prefecture, diatomaceous earth from Ishikawa prefecture,
Acid clay produced in Nagano Prefecture was pulverized to 60 mesh or less and used. No1 to No3 formed based on the above raw materials
Table 3 shows the compounding ratios of the samples.

[0021]

[Table 3]

After the samples No. 1 to No. 3 have been subjected to the processing based on the manufacturing method described in claim 2, the molding pressure is 200 [kg] at a moisture content of the clay of 10 [%] to 11 [%].
/ Cm ² ] and 300 [mm] × 300
A [mm] × 25 [mm] molded body was produced,
It was dried in a drying oven at [° C.] for about 2 hours and fired at 1100 [° C.] using a roller house kiln to produce a ceramic pavement tile having water permeability. Table 4 shows the physical properties of this product.

[0023]

[Table 4]

(Example 2) 1 [mm] of municipal waste incineration ash
After passing through the following sieve, the raw material pulverized to 60 mesh or less and the coarse particles of 1 [mm] to 5 [mm], 5 [mm] or more are similarly sieved, and the raw material pulverized to 60 mesh or less. Was adjusted to adjust the composition. In addition, NaCl + KCl contained in the ash of 1 [mm] or less is 5.0 to 6.0.
[%], Other salts are 7.0 to 8.0 [%],
NaCl + KCl is contained in the ash of 1 [mm] to 5 [mm].
And other salts were hardly observed.
In addition, Otani stone from Tochigi Prefecture was used as a measure against NaCl and salts in ash of 1 [mm] or less. Using this raw material, the raw material was blended, molded, dried and fired in the same manner as in Example 1 to obtain No. 1 and No. 2 shown in Table 5 of 300 [mm] × 300.
A [mm] × 25 [mm] ceramic pavement tile was prototyped.

[0025]

[Table 5]

Table 6 shows the physical properties of the fired samples No. 1 and No. 2 described above. In Table 6, the harmful substance dissolution test is a comparison with the following criteria according to the Environment Agency Notification No. 13. High value chrome mg / l <1.5 Lead mg / l <3.0 Cadmium mg / l <0.3

[0027]

[Table 6]

[0028]

According to the present invention, the following remarkable effects are obtained. 1) As one of the national themes of high value-added reuse of municipal garbage incineration ash containing harmful elution components, stabilize these harmful substances as the most reliable ceramic sintered body, and have water permeability and water retention. It can be used as a construction material with a characteristic to help prevent global warming. 2) Since the Na content is dissolved in the glass, the processing equipment is not corroded, and the quality of the product is stabilized in terms of components and the added value is increased.

Claims (3)

[Claims] 1. NaCl and KCl derived from municipal waste incineration ash are separated and dissolved in a SiO ₂ —Al ₂ O ₃ —Na ₂ O-based glass phase, and the glass phase is 5% by weight or more of the whole. 8
A ceramic sintered body characterized by containing 0% by weight or less. 2. The waste incineration ash is screened with a sieve less than 1 mm,
After sieving to particles exceeding 1 to 5 [mm] and 5 [mm], the above-mentioned sieved material is separately pulverized to 60 [mesh] or less, and a dust collector for a powder and / or refuse incinerator. The fly ash collected in the above is mixed as necessary, and then 0.5 to 1 part by weight of water is added to 1 part by weight of the adjusted powder material, and further mixed to form a mud. 3 to 8 parts by weight of a material containing 60% by weight or more of amorphous SiO ₂ is added to 1 part by weight of anhydrous NaCl and KCl components, and the mixture is cured for 1 to 24 hours. After forming the primary raw material, one or more dry powders selected from slag, selven, glass cullet and clay are used as a secondary raw material in 3 parts by weight of the primary raw material. 5
１1 part by weight is added and kneaded, then molded into a required shape, and
1 hour to 24 at a temperature of 0 ° C or more and 200 ° C or less
After drying for less than an hour, 900 [° C] or more and 1200 [° C]
A method for producing a ceramic sintered body, characterized by firing at the following temperature. 3. The method according to claim 3, wherein the amorphous SiO ₂ is 60 wt.
3. The ceramic sinter according to claim 2, wherein the material containing at least [%] is at least one material selected from zeolite minerals including high silica type clinoptilolite, diatomaceous earth, acid clay, fly ash, and volcanic ash. How to make the body.